How clear do I need to be on Newtonian mechanics in order to understand general relativity?

for example, if I dont understand 3-4 problems per chapter in a book of fundamentals, will it severely hinder me from understanding relativity|||General relativity is non-intuitive and really hard to fully understand. It is really easy to say that the speed of light is constant and that time slows as velocity increases and mass increases as velocity increases, but it doesn't really make a whole lot of sense. So, if you are having trouble with Newtonian mechanics, which does make a lot of sense, then I think you are going to have trouble with relativity.